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The Bogus “Epidemic” of Mental Illness in the US

The Bogus “Epidemic” of Mental Illness in the US

COMMENTARY

Among psychiatry’s critics, the notion that there is an “epidemic” of mental illness in the US is one of the most enduring and widely held beliefs.1,2 More radical versions of the epidemic narrative implicate psychiatrists and psychiatric medication for the alleged proliferation of mental illness2[pdf]—a claim often tied in with the claim that psychiatry has “medicalized normality.”3 But what is the evidence for such an “epidemic” of mental illness in the first place? In discussing this question, it's important to distinguish actual increases in illness frequency from the issues of alleged “over-diagnosis” or “over-medication.” These are important clinical and societal concerns, but are beyond the scope of the present review.

What is an epidemic?
In medical terms, an “epidemic” usually refers to an infectious disease that has spread rapidly to many people—witness, for example, the recent Ebola epidemic. More broadly, an epidemic denotes any illness that appears with a frequency clearly in excess of what is normally expected.4 From the standpoint of medical epidemiology, the supposed “epidemic” of mental illness in this country is largely a myth. But as we will note later, our methods for tracking the occurrence of psychiatric disease over long stretches of time are very limited.

When we speak of an illness’s rate of occurrence, it’s important to understand 2 key terms: incidence and prevalence.4 Basically, “incidence” refers to the number of new cases of the illness within a specific period of time. “Prevalence” refers to the total number of persons sick with the illness during a particular period, regardless of when the illness began—so, prevalence includes both old and new cases of the illness. (The term, “lifetime prevalence” refers to the proportion of individuals in the population who have ever manifested a disorder, and who are alive at a particular time).

Now we are in a position to ask whether, over the past few decades, the incidence or prevalence of psychiatric illness has increased to the point of constituting an “epidemic.” At least with respect to the most serious psychiatric illnesses in adults, the answer is no.5 And recent data suggest this may also be the case in children and adolescents, though, again, our data base is far from ideal.

serious mental illnessElenaYakusheva-Shutterstock
Serious mental illness

While many types of psychiatric illness may be “serious,” the term “serious mental illness” (SMI) is defined by the NIMH as a psychiatric disorder “. . . resulting in serious functional impairment, which substantially interferes with or limits one or more major life activities.”6 Although MDD, bipolar disorder, and schizophrenia are commonly cited as prime examples of SMI, the NIMH definition could apply to PTSD, anorexia nervosa, or any other psychiatric disorder that fits the impairment criteria. While the federal definition of SMI is specific to adults, there is an analogous definition of “serious emotional disturbance” for children.

One method of comparing the occurrence of SMI now with that of years past is via the National Survey on Drug Use and Health (NSDUH)—an annual nationwide survey involving interviews with approximately 70,000 randomly selected individuals aged 12 and older. NSDUH data over the past decade show, overall, very little change in rates of SMI in this country.7-10 For example, in 2013, there were an estimated 10.0 million adults aged 18 or older in the United States with SMI in the past year—representing 4.2% of the adult population.9 This compares with 5.0% in 2010 and 4.8% in 2009.10 And if we go back to the NSDUH data from 2002, we find that 8.3% of adults in the US were found to have SMI during the 12 months before being interviewed.7 So, if anything, it seems that SMI prevalence in this country has actually declined over the past decade or so. Going back farther, there is no reason to revise this conclusion. For example, using other national survey data, a group of technical experts estimated SMI in 1990 at about 5.4% of the adult population.11(pp59-70) Although their methods and data base differed from that of the NSDUH, their findings provide no evidence of worsening rates of SMI over the past 25 years—and certainly no evidence of an “epidemic” of the SMIs that psychiatrists usually treat.

Specific psychiatric disorders
Rates of SMI as assessed by the NSDUH don’t yield incidence or prevalence rates for specific disorders, such as schizophrenia, bipolar disorder, or major depression. However, other sources of information suggest that incidence and prevalence of these conditions, worldwide, have remained fairly steady over the past 50 years.* For example, while rates of schizophrenia differ considerably from country to country, a 1997 review found that overall incidence rates appear relatively stable across countries and cultures, over at least the 50 years studied.12 Similarly, a recent study of the incidence of schizophrenia and other psychoses in England from 1950 to 2009 found essentially “. . . no evidence to support an overall change in the incidence of psychotic disorder over time . . .” although diagnostic shifts away from schizophrenia were reported.13 Neither of these studies points to rising occurrence rates of schizophrenia since the introduction of antipsychotic medication in the late 1950s and the 1960s—much less to an “epidemic” of schizophrenia or other psychoses. Of course, persons with schizophrenia will respond to antipsychotic medication in a variety of ways, and epidemiological data alone are not sufficient to guide individual treatment decisions.

With regard to MDD, data from the Baltimore Epidemiologic Catchment Area study “. . . do not suggest an epidemic of depression” in the period from 1981-2004, although there is evidence that the chronicity of depressive disorder is rising among women in late middle age.14 The period assessed (1981-2004) overlaps substantially with that of markedly increased antidepressant use in the US.15 If antidepressant treatment were truly “driving” an epidemic of major depression—or substantially worsening existing cases—we would expect to see this reflected in rising incidence and prevalence figures. But neither has been detected for the US population as a whole. Further confirmation of the “non-epidemic” of major depression is provided by 8-year NSDUH data.16 These show that the percentage of adults who had a major depressive episode in the past year remained stable between 2005 (6.6%) and 2013 (6.7%).

False indicators of disease occurrence
Some who argue that actual psychiatric illness is on the rise in the US point to increasing rates of psychiatric disability determinations—for example, increased numbers of those “disabled” by mental disorders who qualify for Supplemental Security Income (SSI) or Social Security Disability Insurance (SSDI). Thus, the journalist Robert Whitaker2 used such data to conclude that psychiatric disability rates are now around 6 times what they were in 1955.

This is an interesting finding that bears further investigation. But SSI/SSDI determinations are in no sense a reliable measure of the actual incidence (new cases) or prevalence (total cases at a given time) of psychiatric disorders—nor are they necessarily an indicator of psychiatric treatment success or failure. Disability determinations by the Social Security Administration are largely administrative hearings17not medical-psychiatric evaluations—and are subject to a myriad of confounding variables. The outcome may depend, for example, on how well-prepared the applicant is when presenting his or her “case” to the evaluator—who may or may not have medical or psychiatric expertise.17

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